Two stations A and B are connected via a point to point link. A sends frames to B using Go-Back-N protocol with a window size of 7 and sequence number is of 3 bits. A sends all the frames one by one but B's ACK-3 for frame 3 is not reached to A. But before the timer expires, B received frame 4 and sent ACK-4 but frame 5 is lost and not received by B. So, now what will be frame buffer in the current window of A? ( assume frame number starts from 0)
a) 0 1 2 3 4 6
b) 3 4 5 6 0 1 2
c) 5 6 7 0 1 2 3
d) 5 6 0 1 2 3 4